<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <div id="box">this is <b>box</b></div>
    <script>
      const box = document.getElementById("box");
      console.log(box.textContent);

      setTimeout(() => {
        box.textContent += "this is <b>div</b>";
        console.log(box.textContent);
      }, 4000);
    </script>
  </body>
</html>
